BERLIN (Reuters) -- Germany's economy ministry is not convinced by a plan from General Motors Co. to restructure its European unit, Opel, Spiegel magazine reported on Friday, citing an internal ministry review.

Opel CEO Nick Reilly unveiled a restructuring plan on Tuesday under which the carmaker will invest 11 billion euros ($15 billion) by 2014 and axe 8,300 jobs in a drive to break even by 2011 and make a profit the next year.

"The viability is questionable," Spiegel reported, citing the ministry review, which added that there was a risk of state aid for Opel unjustifiably flowing to its parent company in the United States in the form of licence charges.

Bruederle has repeatedly called on Opel parent General Motors Co. to fund its subsidiary's operations itself, and not just contribute 600 million euros toward the 3.3 billion euros it says it needs to get healthy again.